In recent years, with the diversification of various fragrances and cosmetics, sanitation materials and the like, formerly unknown new demand has been increasing for a fragrance to be used in their scenting (adding fragrance), with requirements that it must be a unique aroma having high palatability, be chemically stable and have excellent compounding ability with other fragrances to be used.
Accordingly, it is markedly important for the fragrance industry to develop a fragrance material which satisfies these requirements.
Up to date, a large number of fragrances have been identified from natural sources and reported; for example, cis-jasmone is frequently used as a high-class jasmine fragrance material because of its excellent fragrance quality.
3-(3Z-Hexenyl)-2-cyclopentenone (2(Z)) is known as a by-product formed during the synthesis of cis-jasmone (4) by, e.g., aldol condensation of 8Z-undecan-8-ene-2,5-dione (3) (Helv. Chim. Acta., 61, 990 (1978), CH 580555 (1976)). Also, it has been reported as a material for synthesizing cis-jasmone by retro-aldol reaction (J. Am. Chem. Soc., 93, 5309 (1971)).
However, 3-(3Z-hexenyl)-2-cyclopentenone (2(Z)) is a by-product unnecessary for the cis-jasmone synthesis and merely recognized as a simple reaction material, and it has not been known that it is markedly useful as a fragrance material. In addition, as for its double bond isomer 3-(3E-hexenyl)-2-cyclopentenone, we found no reports even on the compound itself. 